The present invention relates to a device for securely holding a saw blade of a power saw while loosening or replacing the blade.
Usually, the saw blade of any power saw which has a circular blade, such as a portable power saw, table saw, or a radial arm saw is mounted onto a shaft connected to the saw motor by means of nuts or other tightening elements. When it is time to replace or change the saw blade, these tightening elements must be loosened before the blade can be removed from the shaft. A problem is created during the process of loosening the tightening element. Because the shaft is almost always free to rotate, attempting to rotate the tightening element and thus remove it from the shaft also causes the shaft to rotate, thereby making loosening of the tightening element very difficult. If the shaft can be prevented from rotating, however, the removal of the tightening element is greatly simplified.
One solution for stopping the rotation of the shaft is simply to stop the blade connected to the shaft from rotating. This, unfortunately, is usually accomplished by inserting a piece of wood or other sturdy material into the teeth of the saw blade in the direction of rotation of the blade and then holding the wood in a wedged position between the blade and the inside of the opening of the power tool surrounding the blade. This solution is not without its drawbacks. First of all, it is easy to damage the saw blade--especially carbide tipped blades--by jamming the wood into the teeth of the blade and, even more important, the method is dangerous because it can cause injury to the person changing the saw blade if his hand should slip away from the wood into the teeth of the blade during this process. Similar problems with the shaft turning arise when trying to replace the tightening element after the new blade is in position. In this situation, however, it is even more difficult to hold the blade stationary, because nothing can be wedged between the saw teeth and the opening. The saw teeth are directed in the direction opposite to the tightening motion, so the teeth will not grip into any wedging material as the blade rotates. As a consequence, at the present time there is really no adequate and safe method or means of holding the blade stationary while the nut or tightening device is being loosened or tightened.
Furthermore, once the tightening device is loosened, the blade then must be removed from the shaft. The same problem here arises with regard to the sharp teeth of the blade. Since the blade must be grabbed by hand to remove it from the shaft, the person removing the blade must be especially careful not to injure himself on the teeth of the blade while he is holding it and removing it from the shaft.